As a result of illness, accident or other bodily injury, thousands of otherwise fully ambulatory people become bedridden or otherwise wholly or partially immobilized for varying time periods. During these times of prolonged physical inactivity, the arms and legs of the patient can progressively weaken and become atrophied, and recovery of normal limb movements and strength can be a slow and difficult process. While such difficulties exist for both arms and legs, the process of strengthening the legs to a point where they will carry the full body weight and returning them to a condition suitable for walking can be particularly slow and discouraging for a recovering patient. While the problems associated with returning the bedridden or immobilized patient to a fully ambulatory condition have been long recognized, the medical equipment industry has failed to develop any workable, safe device which can actively manipulate the legs of the patient so as to simulate normal motion such as walking, and most medical rehabilitation efforts have been directed to conventional calisthenics and physical thereapy.
Little attention has been directed toward the production of a powered, controllable device which can actively manipulate the limbs of a patient so as to simulate normal limb movement. For example, it is highly desirable to provide a device which can manipulate the legs of a patient in vertical and horizontal directions to simulate normal walking movement. Such a device would be highly beneficial for increasing the leg strength and degree of leg movement of patients who are virtually unable to move their legs in any substantial continuous fashion.
It is known to construct various passive splint devices such as those shown in U.S. Pat. Nos. 4,323,060, 3,066,322 and 3,661,150 for retaining the legs in various predetermined positions. Similarly, there are numerous passive traction appliciances which retain the legs but permit limited amounts of movement such as those shown in U.S. Pat. Nos. 3,878,842, 3,616,795, 3,800,787 and 3,135,257. All of the devices shown in these patents are intended to retain the limbs in predetermined largely fixed positions and are passive devices. None show an active device which is capable of physically manipulating the limbs along predetermined paths so as to simulate walking or other normal limb activity.
For a human limb manipulation device to be effective, it must be adaptable to the many physical variables encountered among those who will use it. For example, there are numerous semi-mobile patients whose limbs can be moved only through very limited linear or angular displacements without generating intense discomfort or actual tissue damage. The device must be adaptable to closely control the degree of both linear and angular displacement of the limb in order to be safely usable with such patients.
With other patients, the limbs may be marginally controllable by the patient and sometimes will undergo spastic or convulsive movement which may be sharply opposed to the direction of movement of the device. In such situations, the device must be capable of releasing the limb before tender tissues or ligaments are damaged.
Accordingly, while the device must be capable of fairly precise movements and responsive to limb resistance, the mechanism must still be able to move the limb through a wide range of different positions and movements and at varying speeds suitable to the patient's development. It is helpful if the device can be used both while the patient is bedridden and while in an upright position. To permit use of the device in a standard hospital bed, the device must be relatively compact, lightweight and easily movable by a minimum of personnel. It is desirable that the device be capable of manipulating either a single leg or both legs simultaneously so as to simulate truly normal walking movement.
The invention described herein provides a device which meets these needs and can be utilized to return thousands of otherwise bedridden and immobilized patients to an ambulatory condition. It can be used with a bedridden patient at intervals during a prolonged hospital stay to prevent the atrophy and deterioration which can otherwise result in a loss of walking ability.